Air lock device



July 29, 195$v 'RMCDERMQTT 2,845,191

AIR LOCK DEVICE Filed Feb. 5, 1957 FIGZ.

INVENTOR FRAN KLI N McDERMOTT HIS ATTORNEYS United States Patent AIR LOCK DEVICE Franklin McDermott, Darien, Conn., assignor to Lever Brothers Company, New York, N. Y., a corporation of Maine Application February 5, 1957, Serial No. 638,417

7 Claims. (Cl. 214-17) This invention relates to air locks, and, more particularly, to a device for transferring articles into and out of a gas enclosure with a minimum loss or dilution of the enclosed gas.

In the processing of articles requiring an inert gas atmosphere, such for example as canning or bottling, in which articles are to be packed without exposure to air, the transfer of articles and containers into and out of a gas enclosure through an air lock is often accompanied by a substantial loss of valuable gas. In addition, air may be admitted to the enclosure during the transfer operation, diluting the enclosed gas. 7 In this case, replenishment of the gas at frequent intervals is necessary, decreasing the efficiency of the processing operation.

This undesired transfer of air or gas through the air lock takes place when the volume of the chamber within the air lock substantially exceeds that of the article being transferred and especially when the air lock is operated with the chamber empty, as for example, in the successive transfer of articles through the air lock in one direction only.

Accordingly, it is an object of this invention to provide an air lock for transferring articles into and out of a gas enclosure with minimum loss or dilution of the gas.

Another object of the invention is to provide a transfer device wherein the air lock chamber is shaped to fit the articles to be transferred.

A further object of the invention is to provide a transfer device wherein the atmosphere within the air lock chamber may be removed and replaced by another atmosphere during the transfer operation.

These and other objects of the invention are attained by providing an apertured air lock housing and a block having a cavity shaped to fit the articles to be transferred and adapted to fit closely into the housing aperture. The block is arranged to move into and out of the housing to transfer articles through the air lock. A piston mounted within the housing is arranged to enter the cavity to displace or draw in gas through a vent communicating with the outside and inside atmospheres.

Further objects and advantages of the invention will be apparent to those skilled in the art from a reading of the following description of a representative embodiment of the invention in conjunction with the accompanying drawing in which:

Fig. 1 is a perspective view illustrating the arrangement of a typical air lock constructed according to the invention; and

Fig. 2 is a cross-sectional view showing an air lock having a modified cavity and piston.

The air lock shown in Fig. 1 comprises a housing having a rectangular aperture adapted to be mounted in the wall 11 of a gas enclosure or the like so that the aperture forms a passageway into the enclosure. The enclosure may be filled with an inert gas and may include container-filling and sealing devices inside, for example. Two rectangular blocks 12 and 13 are suitably mounted to slide into the housing 10 from either side and are formed with shaped cavities in their internal surfaces which are dimensioned to fit the articles to be transferred, such as cans or bottles. Semi-cylindrical cavities are illustrated in Fig. 1 by way of example. The blocks 12 and 13 fit closely into the housing 10 to minimize gas seepage and they meet at the center of the housing to form internal chambers therein. Each block may be surrounded by a suitable gasket (not shown) to perfect the seal between the block and the housing.

Mounted at the bottom of the housing with their top surfaces normally level with the floor of the housing are two pistons 14 and 15. For a better understanding of the construction of the air lock, the piston 14 is shown in a withdrawn position in Fig. l. The two pistons 14 and 15 have sealing rings and form an air-tight fit within two openings 16 and 17, respectively, in the floor of the housing. The pistons 14 and 15 also form an airtight fit in the chambers formed by the blocks 12 and 13 and they are arranged to be moved vertically in the chambers by suitable driving means (not shown) to displace or'draw in gas. Two vents 18 and 19 in the top of the housing, communicating with the chambers, may each be connected through suitable pipes and valves (not shown) to the atmosphere inside the enclosure, to the outside air, and to a vacuum pump (not shown), alternately.

In operation, the outer block 12 is withdrawn from the housing 10 and articles to be transferred through the air lock are positioned in front of the internal surface cavities by a conveyor or other suitable device. The articles are then moved into the housing and enclosed within the chambers by sliding the block 12 into the housing, the internal block 13 being positioned in the housing at the start of the operation. Air is removed from the chambers by connecting the vents 18 and 19 to the vacuum pump. The valves are then adjusted to admit gas from the enclosure into the chambers releasing the vacuum, and the inner block 13 is withdrawn to permit removal of the articles into the enclosure.

In order to transfer another group of articles through the air lock, the inner block 13 is replaced in the housing and the pistons 14 and 15 are moved upwardly within the chambers to displace gas back into the enclosure through the vents 18 and 19. The vents are then connected to the outside atmosphere and the pistons are moved downwardly drawing air into the chambers. The outer block 12 may thus be withdrawn to transfer the next group of articles without allowing any gas to escape. The transfer of articles out of the gas enclosure follows a reverse procedure with the inner block 13 being withdrawn first. In this case, however, it is not necessary to draw a vacuum before connecting the vents 18 and 19 to the outside atmosphere since the articles being transferred are filled containers occupying substantially all the volume of the chambers. This step may be performed, however, if the vacuum pump is arranged to discharge gas into the enclosure.

As described above, the chambers formed by the cavities in the blocks 12 and 13 are dimensioned to fit the articles to be transferred and the embodiment of the invention illustrated in Fig. 2 is especially adapted for transferring narrow necked bottles into and out of the enclosure. In this embodiment, a bottle-shaped chamber is formed within the air lock by the blocks 12 and 13 which have appropriately shaped cavities in their internal surfaces. The piston 14' has a cap 20 constructed of a flexible material adapted to be compressed to fit closely into the top portion of the chamber. Thus, when the chamber is empty, the piston may be forced into the shaped cavity to displace all the gas in the chamber.

It is apparent that the invention described above provides a highly efficient air lock for transferring articles into and out of a gas enclosure without allowing air to enter or gas to escape.

Although the invention has been described with reference to a specific embodiment, many variations and modifications will occur to those skilled in the art. Accordingly, the scope of the invention is not intended to be limited except as defined by the following claims.

I claim:

1. An air lock comprising a housing, at least one closely fitting block adapted to slide into an aperture in the housing, said block having shaped cavity means adapted to enclose a substantiallycomplementary-Shaped article within the housing, and piston means adapted to move within the cavity to draw in or displace fluid therefrom.

2. An air lock comprising a housing and a pair of closely fitting blocks adapted to slide into apertures in the housing, said blocks each having shaped cavity means and cooperating to enclose a substantially complementary-shaped article within the housing, whereby the article occupies substantially the entire volume of the cavity.

3. An air lock comprising a housing and a pair of closely fitting blocks adapted to slide into apertures in the housing, said blocks each having semi-cylindrical shaped cavity means in one face and cooperating to enclose a substantially complementary-shaped article within the housing, whereby the article occupies substantially the entire volume of the cavity.

4. An air lock comprising a housing, a pair of closely fitting blocks adapted to slide into opposite sides of the 4. housing, said blocks each having shaped cavity means in one face and cooperating to form a chamber to enclose a substantially complementary-shaped article within the housing, and piston means adapted to move within the chamber to draw in or displace fluid therefrom.

5. An air lock comprising a housing, a pair of closely fitting blocks adapted to slide into opposite sides of the housing, said blocks each having shaped cavity means in one face and cooperating to form a chamber to enclose a substantially complementary-shaped article within the housing, piston means adapted to move within the chamber to draw in or displace fluid therefrom, and vent means adapted to conduct fiuid into and out of said chamber.

6. An air lock comprising a housing, a pair of closely fitting blocks adapted to slide into opposite sides of the housing, said blocks each having shaped cavity means in one face and cooperating to form a chamber to enclose a substantially complementary-shaped article within the housing, and piston means adapted to move within the chamber to draw in or displace fluid therefrom, said piston means being arranged to enter one end of said chamber and to fit closely against the other end of said chamber.

7. An air lock according to claim 6 wherein the face of the piston means is formed of a flexible material.

References Cited in the file of this patent UNITED STATES PATENTS 674,685 Payson May 21, 1901 

